Flour milling is a mechanical method of substantially separating and size-reducing the major components of grain kernels. Wheat, for example, comprises a major starchy endosperm, a smaller germ or sprouting section of the seed and a surrounding bran or husk layer. During milling, the wheat kernel is broken open to remove as much endosperm as possible from the bran. The endosperm is then ground or reduced into flour.
Conventional flour milling for most types of grain kernels is typically preceded by a moisture tempering process that raises the moisture content of the kernels to about 10% to 14%. The moisture tempering step typically involves extended soaking times of several hours during which moisture penetrates through at least a portion of the outer bran layers, but does not entirely permeate the grain. Due to this moisture pickup, the outer bran layers become softer and thus more easily separable from the endosperm. However, the temperature of the hydrated grain is typically not closely controlled and can vary depending upon such factors as the storage condition of the grain and ambient storage temperatures, which vary greatly with seasons and mill location. Also, the temperature of the water in which the grain is soaked has an impact on grain temperature as well as the duration of the moisture tempering step. As a result, the tempering step must be carefully monitored and adjusted accordingly, in order to achieve targeted moisture levels in the grain. However, actual milling operations often fail to closely monitor or adjust targeted moisture levels for various operating reasons, such as cost or practicality. The moisture-tempered grain therefore has variable properties when fed to subsequent milling steps.
Subsequent wheat milling steps involve breaking the wheat kernel into progressively smaller fractions using a break system comprised of a pair of counter—rotating break rolls and an associated set of sieves or screens. Coarser fractions are removed by sieves and milled by a subsequent break system to progressively size-reduce the endosperm to produce flour. Each of these milling steps must also be closely monitored and constantly adjusted by skilled millers to accommodate small variations in the incoming tempered grain attributes in order to achieve the desired end products. Adjustments must also be made to each of the milling steps for seasonal or even hourly temperature variations of grain and water as well as the amount of moisture absorbed during the moisture tempering step. Adjustments must also be made at the same time for other varying properties of a natural product, such as size, variety, hardness, and so forth. Such constant fine tuning of grain milling is necessary for continuously running milling operations. However, since adjusting one grain variable in turn affects another, control of milling operations requires great skill, making the process difficult to automate.
As a result, there is a need for a milling process that is not only easier to operate and control, but produces increased yields.